PROJECT SUMMARY/ABSTRACT The primary objectives of the Patient Derived Xenograft (PDX) Core will be to establish and characterize Patient-Derived Xenografts (PDXs), and to support the research aims of the two integrated research projects of the University of California Minority PDX Development and Trial Center (UCaMP), a Minority-PDX Development and Trials Center (M-PDTC). The PDX Core will be responsible for the creation and characterization of 200 PDX models in immune-deficient mice (NSG) from tumors of patients with either gastric, liver, lung, or advanced urothelial carcinoma diagnosed at any of 4 University of California (Davis, Los Angeles, San Francisco, Irvine) NCI-designated Comprehensive Cancer Centers (CCC). More than 60% of the newly established PDX lines will be from tumors harvested from patients representing racial/ethnic minorities. These PDX models will be used to generate cohorts of individual and specific tumor-bearing mice for drug efficacy studies. The PDX Core will be created from the expertise and infrastructure of experienced and capable shared resources at the UC Davis (UCD) CCC (The Mouse Biology Shared Resource [MBSR] and the Biorepository Shared Resource [BSR] and the UC San Francisco (UCSF) CCC (The Preclinical Testing Core [PCT]). UCD will take the lead and coordinate the activities of the two sites (UCD and UCSF) making up the PDX Core. Over the last 5 years, the MBSR, BSR and PCT have been involved in establishing, maintaining, characterizing, storing, and distributing numerous PDX models from human patients (and in the case of UCDCCC, PetDX models from veterinary patients) in dedicated, highly-contained, and infectious pathogen-free environments. In this way, the PDX Core will be integral to the successful development of PDX trial strategies for preclinical testing of single agents and drug combinations that can feasibly lead to clinical validation. The PDX Core will also contribute to the PDX Network (PDXNet) by facilitating the deposition of PDX models, tumors, and data developed at the UCaMP M-PDTC into the NCI Patient-Derived Models Repository (PDMR) at the Frederick National Laboratory for Cancer Research (FNLCR) so that our models can be shared with the wider research community in addition sharing of the PDXs among UCaMP members. In addition, the PDX Core will also work with the PDXNet to develop and validate SOP's for development and characterization of PDX models for pre-clinical testing.